Most older drivers are safe drivers and are less likely than younger people to drive recklessly, at high speeds, or under the influence of alcohol.1 However, motor vehicle injuries are the second leading cause of injury-related deaths among older adults. Very old adults (80 years and over) have higher rates of fatality and injury in motor vehicle crashes per million miles driven than any other age group except for teenagers.1 Therefore, consider safety screening of all very old drivers plus any older adult with certain high-risk medical conditions, including the following.

NEUROCOGNITIVE DISORDERS

Drivers with Alzheimer disease—the most common type of major neurocognitive disorder (dementia) in older adults in the United States—are at high risk for adverse driving events due to impaired memory, attentiveness, problem-solving skills, multitasking, orientation, judgment, and reaction speed. Even in amnesic mild cognitive impairment—a mild neurocognitive disorder without functional decline—driving skills such as lane control may be impaired.2

Frontotemporal dementia, a less common cause of dementia in older adults, is associated with profound impairments in reasoning, task flexibility, planning, and execution. Persons with frontotemporal dementia are more likely to speed, run stop signs, and suffer more off-road crashes and collisions.3

Discuss driving safety with any patient age 80 or older or one with specific conditions

The diagnosis of dementia, however, is less predictive of driving risk than the stage of dementia. The American Academy of Neurology recommends that health care providers clinically “stage” all demented individuals using a validated tool at diagnosis and periodically afterwards. The Clinical Dementia Rating (CDR) scale is appropriate for staging dementia in the office. The CDR has also been shown to identify people with dementia who are at an increased risk of unsafe driving, with strong evidence (level of evidence A) relating dementia stage to driving risk.4 The CDR assigns a score of 1 for mild dementia (function impaired in at least one complex activity); 2 for moderate dementia (function impaired in at least one basic activity); and 3 for severe dementia. Individuals with a CDR score of 2 or higher are considered to be at very high risk if still driving. These persons should be encouraged to surrender their driving privileges.4 Even with mild dementia (CDR score of 1), as few as 41% of drivers may drive safely.4 Most persons with mild cognitive impairment (CDR score of 0.5) are safe drivers.

Patients often have poor insight into their driving safety. However, a caregiver’s rating of driving skills as marginal or unsafe is useful in identifying unsafe drivers (level of evidence B) and can be considered a red flag.4 Predictors with less support in the literature (level of evidence C) include recent traffic citations, motor vehicle accidents, and self-reported situational avoidance, such as limiting driving to familiar roadways. Additional predictors include Mini-Mental State Examination scores of 24 or less, and/or the emergence of an aggressive or impulsive personality (Table 1). A driver evaluation is helpful when there is mild cognitive impairment or mild dementia with at least one red flag.

Clinicians who are not comfortable with staging dementia as mild, moderate, or severe may consider referring to a neurologist or geriatrician.

There is no evidence to support or refute the benefit of interventional strategies such as driver rehabilitation for drivers with dementia.

PARKINSON DISEASE

Individuals with mild motor disability from Parkinson disease may be fit drivers. As the disease progresses, drivers with Parkinson disease may make more errors than healthy elders in visual scanning, signaling, vehicle positioning, and velocity regulation (eg, traveling so slowly that it may be unsafe).5 Clinicians can consider referring a patient with Parkinson disease for a baseline driving evaluation upon diagnosis, and then every 1 to 2 years for reassessment. Alternate transportation should be arranged as the disease progresses.